What type of terrain do you ride?
When I'm home I ride mostly tight lower speed trails, rocky New England stuff. I have no problem w/o the power steering creeping around in stream beds, ravines up and down hills and through fields. Working around my yard the 700 fits the bill. My buddy has a 1000 and in the woods and tight stuff the only advantage he may have is the PS, but I really like the 700. The smaller size is handy in the tight brush and trees as well.
When we go north up into the mountains and start to open them up it's a different story. His easily pulls away going up bigger hills and roads, has a way higher top speed and bottoms less, especially in the front. Doing 25 plus mph every so often I'll bottom out hard in the front on a washout, but I'm guessing he would also at those speeds. I'd probably want aftermarket suspension on the 700 and the 1000.
A thing to note would be his 1000 does seem to run allot hotter than mine, well by seat temperature anyway, especially if someone is in his middle seat, in the summer it's pretty much unbearable. He's added heat reflective tape to help but I think it's still pretty warm.
In saying that, if money was no object and I'm buying for the first time I'd go for the 1000 but I can't justify the money swapping for the 1000 right now, even though I'd like to just for the added power on wide open fire roads and such. I would think the "Fun Factor" would be worth it if I was just buying new. If the mood strikes me hard enough I might do it sooner or latter.
I'm not unhappy with my 700 though. It's a damn good dependable machine so that's why I keep it.